PREFACE: With the readers indulgence, we will explain just what this small book is by first defining what it is not. It is not a compendium of statistics. Neither is it a record of the actual performance of specific dredges of all kinds and under all conditions nor yet a compilation of dredging cost data. Such information is already minutely available in the Annual Reports of the Chief of Engineers, U. S. Army, and in the records of the various departments of commonwealths and municipalities controlling dredging operations in their respective localities. It has been the authors intention first to describe the principal types of dredge in such manner as to impart a fundamental working knowledge of their construction and operation, and then to consider, in concise form, the usual problems confronting the engineer in the conception and accomplishment of dredging projects. Because of the fact that most literatureupon the subject, having been presented in the form of papers and articles in the technical periodicals, isnot onlynot readily available, but incomplete, in that each as a rule treats only of one particular phase of the subject, it is thought that a need exists for a comprehensive treatise, which should be helpful alike to the student and engineer. To fill thiswant hasbeen the authors objective. The importance of the subject, while not always ap- parent to the layman, is obviously paramount, involving the expenditure of many millions of dollars annually for the necessities of commercial life. BALTIMOEE, MD., April, 1920. Content includes: PREFACE CONTENTS PAGE ..- v ., ., .., ., . vii CHAPTER I. DEFINITION AND CLASSIFICATION 1 CHAPTER II. GRAPPLE DREDGES 4 General Description 4 6 The Bucket The Common Grab Bucket Axioms . The Sliding Cross-head Bucket Other Types Grab Bucket Details and Appurtenances Boom, A Frame and Back Guys Spuds, Spud-wells and Gallows-frame The Machinery The House The Hull Operation H CHAPTER III. DIPPER DREDGES 29 General Description 29 The Bucket 29 Boom, Dipper-stick, A. Frame and Back Guys 31 The Spuds ..... 37 The Machinery The Hull Operation 39 ..., ....... 40 ............. 41 Application of the Type 12 High-powered Dipper Dredges 44 CHAPTER IV. LADDER DREDGES 46 Historical 46 General Description 50 Stationary Type 52 Sea-going Hopper Type 52 CHAPTER V. Scows 54 CHAPTER VI. HYDRAULIC DREDGES OF THE RIVER TYPE 58 Radial Feeding Dredge with Spud-anchorage ......... 58 General Description ..... 58 Cutter Head and Ladder . . .... . . .... .... 61 Feeding v ......... 64 Boom, A Frame and Back . . Legs V . 66 The Pipe Line . 67 The Pump . . 71 ix 6 12 13 15 16 20 22 24 24 26 X CONTENTS PAGE Power 78 Method of Design ........ 79 The Machinery 81 Operation . 83 Booster or Relay Pumps 83 Forward-feeding or Mississippi River Type .......... 86 General Description CHAPTER Vll. HYDRAULIC DREDGES OF THE SEA-GOING HOPPER 86 TYPE., 89 Historical . . . . 89 General Description Advantages of the Type Typical Examples . . v . . . 91 PART II DREDGING CHAPTER VIII. OBJECTS AND PHASES OF THE SUBJECT 95 CHAPTER IX. PRELIMINARY ENGINEERING 97 Exploration of Site 97 Estimating the Quantities 100 Choice of Plant and Method of Disposal of Dredgings 107 Plans, Specifications and Contracts 118 Scheduling 121 Estimating the Cost 123 CHAPTER X...